Currently, various light source apparatuses have been proposed for use in projection display apparatuses such as liquid crystal projectors and DMD (Digital Micromirror Device) projectors.
For example, Patent Document 1 discloses a light source apparatus in which excitation light that is radiated from a light source excites a phosphor. More specifically, this light source apparatus is provided with: a light source that radiates blue excitation light that excites a phosphor, and a disk-shaped phosphor wheel to which a phosphor has been applied that radiates fluorescent light when irradiated by the excitation light. The phosphor wheel is divided in the circumferential direction into a red region that is composed of a phosphor that radiates light of the red wavelength when irradiated by excitation light, a green region that is composed of a phosphor that radiates light of the green wavelength, and a blue region that diffuses light of the blue wavelength. The phosphor wheel is provided with a rotation mechanism and radiates red, green, and blue light beams in time divisions by the irradiation of excitation light while the phosphors are being rotated. A condensing lens group that irradiates light beams that are emitted in time divisions in the phosphor wheel into the same light-guiding device is arranged between the phosphor wheel and the light-guiding apparatus (light tunnel) that both receives light from the phosphor wheel and emits the irradiated light that has been converted to light of a uniform intensity distribution. The light emitted from the light-guiding device is modulated by a DMD according to an image signal and then enlarged and projected onto a screen.